1. Field of the Invention
Aspects of the present invention relate to a radio communication system transmitting data from a transmission apparatus to a receiving apparatus, more particularly, to a structure of a data frame for transmitting data via a relay, and a transmission apparatus and a relay using the data frame.
2. Description of the Related Art
With advances in radio communication networks, various services such as a video call and data transmission, in addition to a simple voice call, are provided to use in our everyday lives.
Communication quality in digital communication is determined according to strength of a transmitted signal including data, or a SINR (signal to interference and noise ratio). However, the strength of the transmitted signal including data varies due to characteristics of a radio channel over time. Accordingly, in a conventional mobile communication environment, due to a fading phenomenon, that is a radio channel varies over time, communication quality cannot be guaranteed for a radio channel using a specific service.
To solve the above problem, a technique establishing a predetermined signal to interference and noise ratio (SINR) and controlling the strength of the transmitted signal based on the SINR is provided. However, if a state of the radio channel varies very rapidly, communication quality cannot be guaranteed using such a technique.
To overcome the fading phenomenon, various diversity schemes are provided. Specifically, a spatial diversity technique, which transmits/receives data using a plurality of antennas spatially separated relatively far apart from each other, has been used as an effective and simple technique to overcome such fading phenomenon.
The spatial diversity technique can be used for a terminal having sufficient space for installation of the plurality of antennas such as an access point and a base station, however cannot be used for a terminal without sufficient space for installation of the plurality of antennas.
To solve such a problem, a data transmission scheme using a relay is provided. The relay receives data from a base station, and forwards the received data to a terminal, and the terminal may receive the data via a path whose channel condition is superior, among paths from the base station to the terminal or among paths from the relay to the terminal.
However, there is difficulty to transmit real data since a specific signaling process for determining an optimal path among the paths from the base station to the terminal or among paths from the relay to the terminal, and a data frame structure for determining the optimal path, are not provided.